Seward County Landfill will be first in state to test bio-reactor process

Saturday, 20 February 2010 10:17

By ROBERT PIERCE

Waste typically takes decades to decompose in a landfill, but the director of Seward County’s facility has come up with a way to cut that time in more than half with a new bio-reactor process.

Mike Tabor talked about the new operation at last Monday’s commission meeting, and he said it ties in with a gas project the landfill has been doing for a couple of years.

“Bio-gas is a gas produced by the anaerobic decomposition of organic matter,” he said. “When you cap a landfill, you put it into an anaerobic state or a non-oxygen state.”

Tabor said through research, officials with the Environmental Protection Agency have found that once a facility is put into that state, the degradation process slows or in some cases even stops.

“That’s one of the reasons that they’re re-looking at some of the ways we can handle liquid waste and other things in a landfill,” he said.

Tabor said landfill gas is made up of a mixture of about 50 to 75 percent methane and 25 to 40 percent carbon dioxide, with the remainder made up of elements such as nitrogen, hydrogen sulfide and oxygen.

“The thing about landfill gas is you’ve got a flammable gas in the methane, and you’ve got a non-flammable gas in CO2,” he said. “It’s kind of a different stream of gas than you see anywhere else.”

With most systems of this kind, the two gases have to be split, but with Seward County’s, this is not the case, according to Tabor. He added government officials came out with a Research, Development and Demonstration rule, which Kansas adopted in November. This allowed the state to pass on provisions of a new EPA law.

“The two major changes that are coming about are approval of alternate final covers for landfill cells, which changes closures on landfills and will save thousands of dollars on capping landfill cells by allowing the elimination of geo-synthetic caps and allowing liquid injection to enhance the waste degradation and production of landfill gas,” he said.

Tabor said the Kansas Department of Health and Environment has been approving alternate final covers for some time under another part of the law.

“We repermitted a couple of years ago and actually are already approved for this alternate final cover,” he said. “When we followed this technology and repermitted to do away with that, we put $1 million in the bank by not having to do this.”

Tabor said this puts Seward County a bit ahead of the game on the process’s first stages.

“What we do now on the cap is they require an engineered cap, but it’s all dirt,” he said. “It’s made in certain layers. There’s a drainage layer. There’s a vegetated cover layer. It has to hold a certain amount of moisture. It has to let a certain amount of moisture through. It has to grow vegetation at a certain rate.”

Tabor said there is some extra construction in building a cap, and he said this offsets some of the cost.

“The maintenance is so much cheaper,” he said. “We saved ourselves a ton of money over the next seven, eight years of capping this next cell by eliminating the geo-synthetic caps.”

Tabor said there is currently a push to allow liquids into landfills, which until recently was against federal law.

“We could not let any liquids other than what came in with the trash into a landfill,” he said. “Somebody shows up with a five-gallon bucket of water, we legally couldn’t take it in the landfill. We had to reject it because it was against federal law.”

Landfill officials recently dug up some areas of Seward County’s facility which have been underground for 15 or 20 years, and Tabor said they still look as good as when they were put into the ground.

“It doesn’t degrade like you think it would,” he said.

Tabor said now EPA officials and those from other agencies know that keeping liquid out of landfills was likely not the best technology.

“Under this RD and D rule, they’re going to allow these research projects in these landfills to start with this bio-reactor technology of allowing liquids to go back into a landfill,” he said.

Tabor said this does two things.

“It’s going to start the degradation of the waste, make it faster,” he said. “When that happens, you’re going to generate more gas from that process.”

“The landfill gas is a revenue stream,” he said. “When we degrade this waste over the same footprint of a lined cell, at some point, we’re going to degrade that enough that we can add more waste back in to the same footprint on top of that liner.”

Tabor said the landfill is looking at an industrial waste stream generated by a manufacturing process.

“That waste stream’s currently going to Amarillo at a fairly significant cost,” he said. “This waste stream, by us taking it, is another small revenue source to start this process, get this thing going, generate more gas. We’ve got two or three-fold extra revenue coming in on this project.”

Tabor said when the process is in place, an existing vertical gas well will be used to inject this liquid at the top of the landfill letting it spread out and go down through the waste back to the bottom of the landfill where it will be collected again.

“This liquid has a certain amount of fat in it,” he said. “It’s got a lot of organics in it. That’s exactly the perfect type of the waste we want to put in it. You’re starting the process the minute you put this liquid in it. It works much better than plain water. There are no chemical products in this waste stream.”

Tabor said landfill officials will meet with those from KDHE this week in Topeka.

“We think it’s going to be an exciting project,” he said. “KDHE is very excited about getting one going. We will be the first in the state to do a project of this kind. We’re anxious to see how it’s going to work. I think in the long run, it’s going to be an advantage to us.”

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